Google do_page_fault() and SIGSEV results in a lot of hits. They all point to Omega2, LEDE, kernel 4.1.x. People have reported it happening to dnsmasq, fast-gpio, etc., some said it was fixed but no one pointed out what the problem was.

There was a similar thread that hinted DEVMEM not being configured in the kernel. So I built a LEDE firmware with DEVMEM and DEVKMEM enabled. No joy.